The present invention relates to anti-foaming compositions comprising at least one non ionic defoaming surfactant as well as a solubilizer.
Certain cleaning compositions in industrial cleaning operations, such as the cleaning of bottles or the washing of floors, may lead to the formation of a large amount of foam. This is due in particular to the presence of food soiling or adhesive residues present on the bottles. In order to reduce, or even prevent, the formation of this foam, it is known to add one or more defoaming surfactants to the cleaning composition. Examples of such compositions are disclosed in U.S. Pat. No. 4,070,298. These defoaming surfactants are generally of the non ionic type. However, these defoaming surfactants are of limited use on account of their low solubility in very concentrated alkaline cleaning compositions, which may comprise up to 50% by weight of sodium hydroxide or of potassium hydroxide. Under these conditions, the said defoaming surfactants are sparingly soluble. In order to avoid having to decrease the concentration of alkaline agents to the detriment of the cleaning performance, it is known to combine the defoaming surfactant with agents which make them more soluble, such as cumenesulfonates and xylenesulfonates or organic solvents.
Alkyl polyglycosides have already been described as making non ionic defoaming surfactants more soluble. Alkyl polyglycosides are well-known non ionic surfactants. Their manufacturing process is described, for example, in patent application EP-A-0 077 167. European patent application EP-A-0 489 777 (U.S. Pat. No. 5,025,959) describes an alkali stable foam inhibitor composition comprising polyethylene glycol ethers derived from C16 to C20 even-numbered alkanols, and alkyl polyglycosides, whose alkyl chain comprises from 6 to 12 carbon atoms. On lines 9 to 30 of column 2 of U.S. Pat. No. 5,025,959, it is taught that strongly cleaning formulations consisting in end-capped fatty alcohol glycol ethers with C8 to C12 polyglucoside are foaming too vigorously particularly through the presence of the alkyl glucoside. Until now, the only alkyl polyglycoside compound which is marketed to date, as solubilizing agents for defoaming non ionic surfactants are 50/50 mixtures (by weight) of alkyl polyglycosides having, respectively, an alkyl chain containing 8 carbon atoms and an alkyl chain containing 10 carbon atoms. This type of solubilizing agents, is marketed by the company Union Carbide under the brand name Triton(trademark) BG 10.Alkyl polyglucoside have also been disclosed in U.S. Pat. No. 5,556,573, as a crystallization moderators of fatty alkyl polyglucosides.
A first subject of the present invention consists of an anti-foaming composition comprising a non ionic surfactant and specific alkyl polyglycosides, these compounds making soluble said defoaming surfactants.
According to another aspect, the invention also relates to a cleaning composition comprising an anti-foaming composition based on (i) a defoaming non ionic surfactant and (ii) the said specific alkyl polyglycoside, and to a method for improving the solubility of a defoaming non ionic compound in an alkaline aqueous medium, comprising adding in said medium together with said defoaming non ionic surfactant, an efficient quantity of the said specific alkyl polyglycoside.
The invention thus relates to an anti-foaming composition comprising at least one defoaming non ionic surfactant and at least one alkyl polyglycoside of formula (I):
R(O)Znxe2x80x83xe2x80x83(I)
in which:
R represents a 2-ethyl hexyl radical,
Z is a sugar residue, and
n is between 1 and 5.
It has been observed that such a (2-ethyl hexyl) polyglycoside makes it surprisingly possible, to increase the solubility on the non ionic surfactant in an alkaline medium and therefore makes it possible to reinforce the anti-foaming effect of said non ionic surfactant within said alkaline medium, whereas it is well known, that the compound according to formula (I) has no anti foaming action when it is taken alone. There is thus genuine synergism between the latter and the compound of formula (I).
The residue Z may be chosen from the residues of the following compounds: glucose, dextrose, sucrose, fructose, galactose, maltose, maltotriose, lactose, celobiose, mannose, ribose, dextran, tallose, xylose, and levoglucosan.
Among these compounds, dextrose, fructose and maltose are preferred, glucose being most particularly preferred.
According to an advantageous aspect of the invention, n is between 1.1 and 2.
The non ionic defoaming surfactants according to the invention, are generally chosen from those comprising one or more groups chosen from mono ethoxylated (EO) or poly ethoxylated (PEO) groups, of formula (CH2CH2O)n, and mono propoxylated (PO) or poly propoxylated (PPO) groups, of formulae [CH(CH3)xe2x80x94CH2O]m or [CH2xe2x80x94CH(CH3)xe2x80x94O]m, wherein n and m, which may be identical or different, are between 1 and 50. A non ionic defoaming surfactant according to the invention may contain one or more ethoxylated or propoxylated groups, these groups being distributed in a random or block manner. These ethoxylated or propoxylated groups may or may not be blocked with a C4-C8 alkyl radical, preferably a butyl radical, with a benzyl radical or with butylene oxide. The term xe2x80x9cblockedxe2x80x9d is understood to mean that these groups contain, at the end of the chain, not a hydrogen atom but a radical as mentioned above.
Non ionic defoaming surfactants which are preferred in the context of the present invention may be represented by the general formula:
Rxe2x80x94Xxe2x80x94[(PO)dxe2x80x94EO)axe2x80x94Y]n
in which:
R represents a hydrophobic group preferably chosen from linear or branched alkyl groups having from 6 to 14 carbon atoms;
X represents a nitrogen atom or an oxygen atom;
EO represents an ethylene oxide group (CH2xe2x80x94CH2O);
PO represents a propylene oxide group CH2xe2x80x94CH(CH3)xe2x80x94O or CH(CH3)xe2x80x94CH2xe2x80x94O;
a represents an integer between 1 and 50;
d represents an integer between 0 and 50;
Y represents a hydrogen atom or a blocking group chosen from an alkyl radical having from 4 to 8 carbon atoms, preferably a butyl radical, a benzyl radical, a butylene oxide group;
or alternatively a group (PO)bH or [(PO)bxe2x80x94(EO)cH], in which b and c independently represent an integer between 1 and 50; and
n is equal to 1 when X represents an oxygen atom and n is equal to 2 when X represents a nitrogen atom.
The non ionic defoaming surfactants that are particularly preferred in the context of the present invention are chosen from the group consisting of polyethoxylated amines, polyethoxylated and polypropoxylated amines, polyethoxylated alcohols blocked with a C4-C8 radical, preferably blocked with a butyl radical, or alternatively blocked with a benzyl radical or butylene oxide, and polyethoxylated and/or polypropoxylated alcohols.
The non ionic defoaming surfactants which are most particularly preferred are those of formula (II): 
in which:
R1 is a linear or branched alkyl radical comprising 6 to 14 carbon atoms, preferably 8 to 10 carbon atoms;
a, b and c, which may be identical or different, are integers between 1 and 10.
An anti-foaming composition according to the invention may be in concentrated or dilute, ready-to-use form. When it is in concentrated form, it may comprise from 10 to 50%, preferably 20% to 50% by weight of at least one compound of formula (I) and from 20% to 70%, preferably 20% to 50% by weight of at least one non ionic defoaming surfactant. When it is in dilute form, it may comprise from 0.004% to 10% by weight of at least one compound of formula (I) and from 0.004% to 20%, preferably 0.004% to 10% by weight of at least one non ionic defoaming surfactant. This anti-foaming composition generally comprises a compound of formula (I) and a non ionic defoaming surfactant in a weight ratio of between 1/10 and 10/1, preferably between 1/5 and 5/1 and most preferably around 1.
According to another aspect of the invention, it relates to the use of an anti-foaming composition as defined above as an anti-foaming agent.
According to yet another aspect of the invention, it relates to the use of an alkyl polyglycoside of above mentioned formula (I) as a solubilizing agent for a non ionic defoaming surfactant.
According to yet another aspect of the invention, it relates to cleaning compositions comprising an anti-foaming composition as described above. This cleaning composition according to the invention usually comprises from 2 to 50% by weight of one or more alkaline agents. The alkaline agent used in these compositions is usually sodium hydroxide or potassium hydroxide. The cleaning compositions according to the invention may contain an anti-foaming composition content which is such that the concentration of non ionic defoaming surfactant in the said cleaning composition is between 0.001 and 2% by weight.
According to a last aspect of the invention, it relates to a method for improving the solubility of a defoaming non ionic compound in an alkaline aqueous medium, including the following steps:
a) preparing a mixture of at least one defoaming non-ionic surfactant with at least one compound of the formula (I)
b) mixing said mixture within an alkaline aqueous medium.